Problematic renal calculi presenting during pregnancy.

Urinary tract calculi presenting during pregnancy are rare, with less than 0.1% of pregnancies being associated with stones, the vast majority being asymptomatic and a chance finding. We outline six cases treated over an 8-year period. They presented with combinations of pain, sepsis and obstruction. Intervention was required in four cases: insertion of antegrade nephrostomy, double-J stent, Dormia basket stone extraction, open pyelolithotomy and induction of labour. In each case the pregnancy had a successful outcome. Renal colic can precipitate premature labour. Delayed diagnosis and intervention can result in permanent renal impairment. Ionising radiation and anaesthetic agents may be harmful during pregnancy. The problem is rarely encountered and we therefore present information on the relative risks in each trimester of exposure to the mother and fetus and present a clinical algorithm for the management of these patients.