Common Medical On-Call Scenarios and Jobs

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This guide covers some of the most common scenarios you will be asked to see during a medical on-call shift.

This guide is not an all-encompassing account of how to manage each situation, but it aims to give some helpful initial tips and considerations when faced with common problems.

This article is part of our preparation for practice collection, designed to support newly qualified doctors and doctors working in new clinical settings πŸ₯

Prescribing IV fluids

One of the most common tasks you will be asked to do during an on-call shift is to prescribe IV fluids (‘chart IV fluids’ or ‘re-write IV fluids’).Β 

In an ideal world, the indication and plan for a patient’s IV fluid regimen should be clearly documented (and charted) by the patient’s medical team within regular hours. However, unfortunately, this is not always the case, and it falls to the on-call medical team to review the need for ongoing IV fluids.

Fluid prescribing can be complicated, so check out our dedicated guide to IV fluid prescribing for a full rundown.


In an β€˜on-call’ situation, you are often very time-pressured and may not have time to do a complex fluid review on every patient who is on IV fluids. Having said this, it is never appropriate to β€˜blindly’ prescribe further IV fluids without assessing a patient.

There is some critical information that needs to be gained from the nursing staff when asked to chart IV fluids. If the nursing staff are unable to tell you this information, it will be available with a quick glance through the patient record.

Key questions

The following questions will give you most of the information you need to triage the request:

  • What is the indication for the IV fluid that is currently running? Is it resuscitation, replacement or maintenance fluid?
  • Is the patient able to maintain their own oral fluid intake? Are they on a strict input/output chart? Are there any excess losses that need to be considered (e.g. ongoing diarrhoea)? Are they nil by mouth or unable to drink for any other reason (e.g. decreased GCS)?
  • What are the patient’s observations, including urine output measurements? Ensure urine output is monitored, remembering >0.5ml/kg/hr is the minimum acceptable urine output.

Some patients will very clearly need ongoing fluid prescriptions during the on-call shift. These include patients with acute kidney injury of suspected pre-renal origin or patients that are nil by mouth and require ongoing maintenance therapy.

Hydration status assessment

In these cases, it is best practice to perform a quick hydration status assessment to ensure the patient is not developing fluid overload (most importantly, assess JVP, lung bases and look for peripheral oedema) and then chart ongoing fluids to match the patient’s needs based on the NICE algorithm.

If there are signs of developing fluid overload, fluids may have to be paused, or the rate decreased, depending on the clinical scenario.

Some patients may require further investigations to determine whether they need ongoing fluid therapy, for example, patients having electrolyte replacement. These patients should generally always be handed over by their team for a repeat set of blood tests and clear criteria for continuation/cessation of IV electrolyte replacement.

For more information, see our dedicated guide to electrolyte replacement on the ward.

Not prescribing IV fluids

There are many situations in which patients will not require further IV fluids charted during the β€˜on-call’ period.

These are generally patients who have had some supportive IV fluids early in their admission (often started in an emergency when a patient’s presentation is undifferentiated), but are now able to support their own fluid intake with no signs of dehydration/kidney injury (adequate urine output) and no excess ongoing losses.

If there is no clear indication for ongoing IV fluids, and the team has not documented a plan, it is often safe to wait until the patient’s team returns to decide on ongoing fluids (remember, most humans do not drink overnight at home!).

Remember that IV fluids can cause harm when overused.

Reduced urine output

It is very common to be alerted to a patient with reduced urine output whilst on the medical ward, and this can occur for a range of reasons.

Urine output is monitored as it provides valuable information about end-organ perfusion. Decreased urine output can be an early indicator of end-organ hypoperfusion, as urine output drops off rapidly when the kidneys do not receive enough blood supply.

For example, urine output is used to monitor patients with sepsis. Appropriate early assessment and response to a decreased urine output can improve patient outcomes.

Clinical context

To understand the significance of decreased urine output, you must first understand the clinical context in which the urine output is being measured. The most common examples on a medical ward would include:

  • Hypotension (e.g. sepsis): reduced urine output may indicate hypoperfusion of end-organs, requiring fluid replacement or possibly vasoactive agents.
  • Acute kidney injury: reduced urine output may indicate worsening AKI, requiring more IV fluid in the case of early pre-renal AKI, or potentially requiring renal replacement therapy if fluid overload develops.
  • Congestive cardiac failure exacerbation: reduced urine output may indicate a failure of diuretic medications or overuse of diuretic medications leading to dehydration.

It is important to consider the method by which the urine output is being measured. If measured in bottles, patients can go long periods without passing urine in a normal state (it is expected to pass urine at least every six hours, although this may not happen overnight).

Catheterisation allows a much more accurate idea of urine output on an hourly basis, and if there is decreased urine output measured over two consecutive hours, this is usually significant.


When asked to review a patient with decreased urine output, familiarise yourself with the patient’s background and current clinical picture. Does the patient have risk factors for the development of AKI (e.g. chronic kidney disease, admission with sepsis or hypotension)?

The next key step is to perform a thorough hydration status assessment. In most patients, it is essential appropriate to perform some basic further investigations:

  • Bladder scan: ensure the reduced urine output is not secondary to urinary retention / blocked catheter.
  • Urea & electrolytes +/- VBG: to assess electrolytes and renal function (creatinine), and consider assessing pH/lactate if suspecting hypoperfusion.

The results of the above assessments should give you enough information to implement an appropriate action plan.

For example, in a septic patient who appears clinically dry, a trial of an IV fluid bolus can be used to restore circulating volume and assess the impact on urine output (the patient should ideally be catheterised for accurate urine output monitoring).

In a stable patient who appears clinically well, with no signs of dehydration and no risk factors for kidney injury, it may be appropriate to encourage oral fluid intake and assess response before taking blood tests.

Heart failure

Reduced urine output in a patient with heart failure can be a more challenging clinical scenario.

A patient who looks grossly overloaded (raised JVP with significant oedema) is likely to need more diuretics. However, those with signs of intravascular depletion (JVP not raised, dry mucous membranes) may need their diuretics withheld or even a small amount of IV rehydration. These patients are tricky, and you should discuss them with a senior doctor if concerned.

Any patient with reduced urine output should have a clear management plan for the remainder of the on-call shift and should be handed over to either the next on-call team or the patient’s own team (e.g. in the AM handover) to assess progress following initial intervention.

As decreased urine output can be an early warning sign of deterioration, do not hesitate to discuss with your senior doctor if you have any questions regarding your potential management plan.


If a patient falls on the ward, it is usually mandatory for the medical team to review them.Β 

Triaging these reviews is mainly done via communication from the nursing staff. Try to get as much collateral from the nursing staff as possible. Often, someone would have witnessed the fall.

If the nursing staff tell you a benign history, have been able to get the patient back into bed, and have minimal ongoing concerns – these patients can likely wait for you to finish your urgent tasks before review.

For completeness, it is worth asking the nursing staff to perform an ECG (mandatory in some hospitals post-fall) and a lying & standing blood pressure (most falls in hospital will occur soon after the patient has got up from bed). The patients should also be kept on neuro-obs and under close observation until they have been reviewed.

Occasionally, you will be called to review a fallen patient who remains on the floor due to concern about spinal or other injuries. These patients will require rapid assessment as soon as you can safely leave your other patients.

When reviewing the patient with a fall, two key questions need to be answered:

  • Why did the patient fall?
  • Have they suffered any serious consequences from the fall?

Why did the patient fall?

It is important to gather as much history surrounding the event as possible.

Many of the patients that fall in hospital are elderly with cognitive impairment and may not be the best historians. If the patient is able to give a history, take a full fall history to assess for any suggestion of a pathological cause (e.g. syncope, seizures).

Often, allied health staff will have witnessed the fall and can tell you if it appeared to be a benign trip/slip or whether the patient showed any atypical behaviours before the fall.

Even if the fall sounds benign, an ECG and a postural blood pressure should be performed. If the ECG is abnormal or there is any suspicion of syncope, these patients should be placed on telemetry monitoring and discussed with a senior doctor. It is also essential to review the drug chart to look for any culprit medications or polypharmacy that may be making the patient drowsy or confused overnight.

Have they suffered any serious consequences from the fall?

A broad top to toe examination is important for any patient with a fall. Look for any signs of head injury, even if the patient denies hitting their head.

A full neurological examination to assess for any focal weakness suggesting intracranial events is also important. If there are any signs of focal neurology, these patients should be discussed with a senior and neuro-imaging urgently organised. This will also be required for all patients with a suspected head injury on anticoagulation (e.g. warfarin or DOACs).

It is important to palpate all long bones and the hips to assess for potential fractures and also to palpate the abdomen for possible traumatic abdominal injuries.

For the fallen patient on the floor, it is important to understand the principles of how to assess the cervical spine. If you are unable to clear the C-spine or have any doubts surrounding this clinically, the patient should be treated with full spinal precautions and returned safely to their bed, and spinal imaging should be arranged. If there is any form of upper or lower limb neurology, this is an emergency and should be discussed with senior doctors.

All patients who have fallen out of hours should be handed over to the medical team during the next morning’s handover. A fall on the ward is always significant, and patients should have an early morning review.

The aggressive patient

The medical wards at any hospital have a large population of elderly patients, often with a history of dementia or cognitive impairment. These patients are extremely vulnerable to delirium when hospitalised, and in some cases, this can lead to extremely challenging behaviour on the ward. A common ward call will be to assess a combative/aggressive patient.

If this is a new behaviour in a patient who was previously not known to be delirious, this represents a change in clinical state, and the patient should be investigated to identify anΒ underlying cause (delirium/infection screen, etc). Unfortunately, this is not always immediately possible due to severe agitation, and patients must be calmed to allow proper medical investigation.

All hospitals will have a security emergency system, which has often been activated by the time the doctor is called, meaning there is security staff on the ward. This team will have been trained in how to de-escalate situations. However, as the doctor, it is your role to assist with the de-escalation process.

Some patients will respond much better to doctors than to security personnel. However, it is important not to put yourself in danger to achieve this goal (i.e. do not isolate yourself in a room with a combative patient).

Management of aggression

Each hospital or trust will have a specific protocol to follow when it comes to the management of aggression on the ward. In an acute situation during an on-call, your priority is to keep the patient safe alongside the rest of the ward patients and the ward staff.

When dealing with these patients, the general principle is to use the least restrictive methods possible to control agitation.

Verbal de-escalation

Most patients can be verbally de-escalated / re-directed without using physical force or chemical restraint. Sometimes, there will be a clearly identified issue that aggravates the patient, which can be removed and the problem solved. Verbal de-escalation is always the best outcome, even if it is very time-consuming for the staff on the ward. Patients will often need a 1:1 β€˜sitter’ to watch over them, which can always be requested from the hospital manager.

The reason for this aggression is not always clear in a confused patient. Commonly, it relates to wanting to leave the hospital when this will put them at risk of serious harm, and the patient clearly lacks the mental capacity to make this decision for themselves.

Chemical sedation

If the patient is not settling with verbal de-escalation techniques and they are an ongoing risk to themselves or others, they are likely to need chemical sedation. Note that it is not appropriate to use chemical sedation in the on-call situation simply to manage verbal aggression or patient distress – the patient must clearly be at risk of hurting themselves or others.

Depending on the severity of the behaviour, chemical sedation can be first offered in the form of an oral sedative agent (e.g. PO diazepam or PO risperidone). However, these can take a long time to act effectively.

If a rapid effect is needed, follow your local rapid tranquilisation guidelines to give an intra-muscular agent (e.g. IM lorazepam is an appropriate first-line choice for most people). Note these medications should not be repeated in short succession, as they will also take time to work (follow your hospital guidelines – generally, you should not give another dose of lorazepam within 1 hour of the first dose).

There is clear evidence that using sedative medications leads to an increase in mortality in elderly populations, and thus, every measure should be taken to avoid this where possible.

Document clearly in the medical notes why it was necessary (i.e. the specific risk of harm to themselves / others), and the other failed options.

It is best practice to try and discuss with the family where possible and explain the rationale behind the use of chemical sedation. Family members are often willing to come in at all hours to try and settle their loved ones, which can be an incredibly effective option.

Ongoing management and review

Any patient who has had sedative medication administered out-of-hours will need to be handed over to the day team for early review. Elderly patients will likely be more amenable to medical examination/investigations during normal waking hours.

There should be a clearly documented plan approved by the patient’s consultant for chemical restraint if required ongoing. If the situation is ongoing and persistent, there are legal implications that will need to be considered by the medical team (e.g. deprivation of liberty safeguards).

Prevention of delirium

It is always worth remembering that prevention is better than cure in these circumstances, and particular care should be taken to prevent the development of delirium in at-risk populations in the hospital. Many hospitals will have a specific delirium screening tool and care plan.

After-hours prescribing

During the medical on-call shift, the nurses will ask you to prescribe various medications. Many of these will be a patient’s regular medications. However, there are a few specific challenges or things to consider.

Regular medications

Prescribing a patient’s regular medications will often fall to the on-call team when a patient is newly admitted to the ward. This is usually straightforward, and the patient may have a list of their medications with them. However, it is essential to remember that hospital admission represents a change from the patient’s β€˜regular’ state, and their regular medications may no longer be appropriate.

Examples of when regular medications can cause harm

A patient admitted with dehydration and acute kidney injury should not be prescribed their regular diuretic medications, as this will worsen the hypovolaemia.

A patient admitted with sepsis and hypotension should not have their normal anti-hypertensives prescribed, as this will worsen their hypotension.

Always ask a senior doctor if you are unsure. If the medication is not due until the next morning, it is often safe to chart the medication and box the administration for β€˜review’. The patient’s medical team will then be able to review this in the morning before the dose is given.

If a patient’s regular medication is to be withheld on admission to hospital, it is best practice to first chart this and then withhold the doses to be administered on the medication chart with a specific review date. This prevents the medication from being overlooked completely and not re-introduced upon discharge.


When asked to prescribe analgesia for a patient, it is important not to prescribe further analgesia blindly but to consider the patient and their need for analgesia.

Always ask the nursing staff why the patient requires analgesia, as the patient may have new chest pain or abdominal pain that needs further investigation. Any new source of pain or escalation of previous pain is a concerning symptom that requires review.

In general, the WHO pain ladder should be followed when prescribing analgesia in hospital. Always start with oral paracetamol unless there is a contraindication, as this is safe and effective in almost all populations (even in most patients with liver disease, although always discuss with senior members of the medical team if concerned).Β 

Elderly patients

Be cautious with analgesia prescribing in the elderly. Elderly populations are much more susceptible to the adverse effects of NSAIDs (gastrointestinal/renal), and these are generally avoided for this reason.

The elderly are also much more sensitive to opiate-based medications. Opiate medications are often required when paracetamol does not control pain. However, make sure that elderly patients are started on very small doses of weak opioids and response is assessed.

If charting opioids for elderly patients, always also chart prophylactic laxative therapy (severe constipation is common).


Warfarin is most commonly given at 18:00 and requires daily dosing whilst in hospital. Again, this is ideally charted by the patient’s own medical team. However, occasionally, this gets missed and will require charting by the on-call team. Unfortunately, this is not always a simple task and requires some investigative work.

Warfarin prescribing can be tricky, and true competence only comes with experience. The more data you have to guide this decision, the better.

Never prescribe the same dose that was prescribed yesterday and assume this will be the correct dose. Always ensure an up-to-date (ideally same-day) INR, as warfarin levels are notoriously labile in hospitalised patients.

Ensure that there are no contraindications to anticoagulation that have been overlooked when the warfarin was charted (e.g. upcoming surgery).

INR in range

If the INR is around the desired range, track the daily trend of the INR and map this against the dose of warfarin given.

If the patient has been on a stable dose, but the INR is slowly rising to the top end of their therapeutic range, they will likely require a slight dose decrease, or vice versa, if the INR is falling.

Always remember that the patients on warfarin are also often a great source of information!Β TheyΒ will be able to tell you their regular dosages and what they would usually take to maintain a normal INR.

High INR

If the INR is markedly high, it is important to withhold warfarin and check for any signs of bleeding. Your hospital will have a policy regarding when to administer vitamin K or other reversal agents (always know how to find the guideline library!).


If the INR is markedly low, consider the need to β€˜cover’ with low-molecular-weight heparin (LMWH) for patients at higher risk of clots (e.g. mechanical heart valves or recurrent thrombotic events). These patients will likely need a higher warfarin dose.Β 

However, remember that the INR can take a long time to increase (multiple days, highly variable amongst patients), so if there has been a recent increase, keeping the same dose and monitoring response may be appropriate.

Warfarin prescribing is undoubtedly complex, and if you are unsure at any point, this should be discussed with a senior team member. Remember to have all recent dose and INR data available at the time of discussion alongside the indication and target INR range. For a full summary, see our dedicated guide to warfarin prescribing.

Verifying death

Verifying (confirming) death is a common on-call task for doctors. For more information, see our detailed guide to confirming death and documenting death confirmation.Β 


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