QuestionSBA
QuestionChoice
Incorrect - Sacral splanchnic nerves arise from the sacral sympathetic chain. They provide both motor and sensory innervation to the posterior thigh, part of the pelvis, and the majority of the lower leg and foot. They do not typically innervate the bladder, and damage to these nerves is not associated with urinary retention.
10008266
b
Damage to sacral splanchnic nerves
QuestionChoice
Correct - The pelvic splanchnic nerve is made up of preganglionic parasympathetic fibres that arise from the S2-4 nerve roots of the sacral plexus. The internal urethral sphincter is supplied by the pelvic splanchnic nerves. The pelvic splanchnic nerves can trigger contraction in the detrusor muscle of the bladder and trigger micturition. As the patient is able to sense his bladder is full but unable to void urine voluntarily, his pelvic splanchnic nerves are likely damaged.
10008265
a
Damage to pelvic splanchnic nerve
QuestionChoice
Incorrect - The phrenic nerve provides motor innervation to the diaphragm. It does not supply the bladder, and therefore damage to the phrenic nerve would not lead to urinary retention.
10008267
c
Damage to the phrenic nerve
QuestionChoice
Incorrect - It is unlikely that a bladder stone is the cause of this patient's inability to void given the history of recent trauma. Bladder stones typically present with suprapubic pain and haematuria, making this option highly unlikely.
10008268
d
Bladder stone
QuestionChoice
Incorrect -  Damage to the pudendal nerve is likely to cause urinary incontinence rather than an inability to void. The pudendal nerve controls the external urethral sphincter and is responsible for maintaining continence.
10008269
e
Pudendal Nerve
Concept
Chapter
2693
4414
Acute Urinary Retention
Topic
142
Nephrology
14200
A 25-year-old male motorcyclist suffered a road traffic accident, sustaining multiple fractures to the lower part of his sacrum from S2 inferiorly. Whilst in the emergency department after the accident, he is able to sense that his bladder is full but is unable to void urine.

Which of the following is the most likely cause of his urinary retention?
a