Pelvic Organ Prolapse: This condition is common in postmenopausal women and can cause sudden urinary retention due to the prolapse of the uterus or bladder into the vagina, obstructing the urethra.

Urinary Tract Infection (UTI): A UTI can cause irritation and swelling of the urethra, leading to urinary retention. This is more common in women, especially postmenopausal due to hormonal changes.
Constipation: Severe constipation can put pressure on the urethra, causing urinary retention. This is a common issue in older adults due to decreased mobility, dietary changes, and other factors.
Medication Side Effects: Certain medications, such as anticholinergics, antihistamines, and some antidepressants, can cause urinary retention as a side effect.

Spinal Cord Injury or Compression: Although less common, any form of spinal cord injury or compression (e.g., from a herniated disk) can lead to sudden urinary retention. Missing this diagnosis could result in permanent neurological damage.
Cauda Equina Syndrome: This is a serious condition where the nerves in the spinal canal are compressed, leading to symptoms including sudden urinary retention. It requires immediate medical attention to prevent long-term damage.
Ovarian Torsion or Other Acute Abdominal/Pelvic Conditions: While less likely to cause urinary retention directly, conditions like ovarian torsion can lead to severe abdominal pain and indirectly cause retention due to pain and positioning.

Tumors (e.g., Uterine, Ovarian, or Bladder Cancer): Although rare, tumors in the pelvic area can grow large enough to obstruct the urethra, leading to urinary retention.
Neurological Disorders (e.g., Multiple Sclerosis, Parkinson's Disease): Certain neurological conditions can affect bladder control, leading to urinary retention. However, the onset is usually more gradual than sudden.
Foreign Body in the Urethra: This is an extremely rare cause of urinary retention, usually seen in cases of accidental or intentional insertion of objects into the urethra.