ABC of antenatal care. Abdominal pain in pregnancy.

Abstract

Inevitable miscarriage. Pain in the stomach brings a woman to her doctor's surgery early, especially when she is pregnant. In most such cases the problem is not serious, but all cases need careful assessment as some women will need an immediate opinion at the hospital, some can wait till the next day, and others can wait till the next antenatal clinic. Abdominal pain is diagnosed mostly by clinical means. The history and examination are most important, investigations being less helpful than in other branches of medicine. The use of ultrasonography by clinical gynaecologists has considerably improved the understanding of pelvic pathology. A vaginal transducer may give better images in early pregnancy than abdominal transducers; however, the laparoscope is still a major investigative tool for lower abdominal pain in early pregnancy. Under appropriate anaesthesia a good view of the pelvis and its organs clinches a diagnosis; in some cases treatment is also possible at the same time. Pain arises either from inside an organ, involving the covering visceral peritoneum or from later involvement of the parietal peritoneum. The visceral aspects of the pain are poorly localised as they are mediated by the autonomie nervous system. Once the parietal peritoneum is affected, however, impulses travel by the somatic route and localisation may be more specific. Nausea and vomiting occur early in many pelvic conditions as well as in normal pregnancy, which might confuse the picture. Abdominal distension is not usual unless the alimentary tract is involved secondarily; furthermore, it is masked in mid and late pregnancy by the enlarging uterus. Shock may occur if acute pain is accompanied by sudden deterioration in the woman's condition such as in real hypovolaemia due to blood loss at a ruptured ectopic pregnancy or in relative hypovolaemia after excessive autonomie stimulation from peritoneal irritation of an abruptio placentae. For the sake of analysis, in this article the commoner causes of abdominal pain in pregnancy are considered as occurring in either late or early pregnancy, but some conditions can occur in both. The causes will be considered under only one heading, which does not mean, however, that they do not occur in the other half of pregnancy.