17 - Urological problems in pregnancy

Summary

The most common urological symptoms in pregnancy are a consequence of pregnancy on a normal urinary tract rather than specific urological diseases presenting in pregnancy. However, both the diagnosis and management of urological diseases in pregnancy can be complex. This review will discuss aetiology and management of loin pain, urinary frequency, urinary tract infection (UTI) and haematuria. Additionally, imaging of the renal tract, renal stone disease, urinary tract malignancy and the management of women with urinary tract diversion or reconstruction in pregnancy will be specifically addressed. Postpartum complications affecting the urinary tract, such as fistulae and urinary incontinence, are not in the remit of this review.

Physiological changes to the urinary tract in pregnancy

Upper tract

The increase in cardiac output, total vascular volume and renal blood flow in the first and second trimesters of pregnancy leads to a 40—65% increase in glomerular filtration rate (GFR). As a result, the kidneys increase by up to 1 cm in length and 30% in volume. The increase in urine production coincides with hormonal and mechanical changes to the maternal renal pelvis and ureter. A ‘physiological hydronephrosis’ of pregnancy occurs in more than half of pregnancies in the middle trimester. Less commonly, ureteric dilation has been observed as early as 7 weeks of pregnancy and may be due to a relaxant effect of progesterone. At this early stage of pregnancy, ureteric dilation does not equate with obstruction, whereas mechanical extrinsic compression can occur from second trimester onwards owing to both the gravid uterus and the engorged ovarian vein plexus crossing the ureter at the level of the pelvic brim.