INTRODUCTION

During the childbearing process, the gastrointestinal (GI) system is affected both by the hormones of pregnancy and by its displacement by the growing fetus. It is not uncommon therefore for the pregnant woman to complain of, e.g. abdominal discomfort and changes to bowel habits. It is also as likely during pregnancy as at any other time of the woman’s life that she develops problems related to the GI tract, such as appendicitis or cholecystitis. The midwife must therefore be vigilant to the possible causes – the differential diagnoses – of both pregnancy and non-pregnancy related conditions.

This chapter looks both at medical conditions related to the gastrointestinal system that may occur at any time in an individual’s life and at those unique to pregnancy and childbirth.

RELEVANT ANATOMY AND PHYSIOLOGY OF THE GASTROINTESTINAL TRACT

Relatively common conditions experienced by the pregnant woman relate principally to the small and large intestines of the GI tract. These include inflammatory bowel disease and irritable bowel syndrome. Crohn’s disease, one of the inflammatory conditions, can affect the entire length of the GI tract but in the early stages of the disease tends to affect the intestines. This section will therefore discuss this area of the GI tract only.

The small intestine extends from the distal sphincter of the stomach to the ileocaecal sphincter at the junction with the large intestine (Fig. 12.1). The small intestine is divided into the duodenum, jejunum and ileum, which are each highly adapted to digestion and absorption. The walls of the small intestine are folded (Fig. 12.2) to produce a large surface area for these processes. Glands secrete mucus and fluids, and the brush border provides enzymes to reduce proteins, carbohydrates and fats to their basic components for ease of absorption.

Figure 12.1 The gastrointestinal tract.

Figure 12.2 Microstructure of the small intestine.

The large intestine, the caecum, colon, rectum and anal canal, extends from the ileocaecal sphincter to the anus. This section of the gastrointestinal tract is responsible for absorption of water, electrolytes and vitamins, thus concentrating the faeces to prevent loss of fluid from the body. Some final chemical digestion is performed by resident bacteria. Waste products in the form of faeces are then eliminated from the body by defecation, through the anus.

INFLAMMATORY BOWEL DISEASE

Inflammatory bowel disease (IBD) is on the increase in the developed world and thus an increasing number of women are becoming pregnant with this disorder. Inflammatory bowel disease includes the two conditions: ulcerative colitis and Crohn’s disease.

The cause of this disease is unknown. There appears to be a genetic predisposition to the condition but it is thought to be an autoimmune disease – the patient’s own immune system attacks the intestine causing inflammation. Both conditions commonly first occur in young people in their teens to 20s.

Ulcerative colitis is a disorder of the colon and rectum in which there is severe inflammation and oedema of the intestinal mucosa. Ulceration develops and the individual suffers from diarrhoea, urgency and abdominal pain. Ulcerative colitis varies in intensity and severity between individuals. The more severe forms result in malaise, fatigue and weight loss. Complications of the condition include anaemia, tachycardia, fever and dehydration.

Crohn’s disease can affect any part of the gastrointestinal tract and is characterized by inflammation and ulceration of the entire depth of the wall of the intestine. Commonly, it affects the small intestine preventing adequate absorption of nutrients. Typically, the individual suffers from acute episodes of illness with long periods of mild and intermittent symptoms. During the acute stage, the individual suffers severe inflammatory symptoms of cramping pain, diarrhoea, flatulence, nausea and fever.

Treatment of both conditions can be medical or surgical. Medical treatment involves the use of anti-inflammatory and immunosuppressant drugs and steroids. Surgery includes removal of the affected part of the intestine. This may cure ulcerative colitis as once removed it does not recur. In Crohn’s disease however, surgery will only be undertaken if there is no other possible treatment, as there is a high incidence of recurrence. Generally surgery involves removal of the affected area and an anastomosis of the two healthy ends although a colostomy/ileostomy may be required (Box 12.1).

Both of these conditions can cause problems outside the gastrointestinal tract such as skin rashes, arthritis and inflammation of the eyes. There is an increased risk of gastrointestinal cancer. Both of these diseases are characterized by remissions and exacerbations. Inflammatory bowel disease can be very disruptive to the lives of the individuals who suffer from it. It affects the ability of the individuals to eat, participate in social and work activities and can have a major effect on the individual’s character.

INFLAMMATORY BOWEL DISEASE AND CHILDBIRTH

The peak onset of inflammatory bowel disease is between 20 and 40 years of age and thus the impact of the disease on pregnancy is an important clinical issue. Generally, both diseases are thought to follow a similar course that existed before conception, i.e. if in remission, this will continue through pregnancy, while active disease is likely to complicate pregnancy leading to increased maternal and fetal morbidity (Bush et al 2004). The risk of a relapse during pregnancy is considered to be 33%, which is no higher than in those not pregnant (www.crohn’s.org.uk). A relapse is more likely during the first trimester of pregnancy and postnatally. Those individuals who have an ileostomy may find some dysfunction in the later stages of pregnancy when the growing fetus displaces the intestines.

Drugs used in the treatment of IBD are relatively safe for use in pregnancy – certainly the risks of the disease are higher than the risks from the medicines used to keep the condition in remission (Langarragard et al 2007). However, some studies have shown an increase in congenital abnormalities (Alstead & Nelson-Piercy 2003).

Supplementation with folic acid will be advised, as this vital substance for fetal development may not be adequately absorbed by the damaged gut.

Breast-feeding is not contraindicated either by the medication or from the effects of the disease process on the mother. The risk to the neonate of inheriting IBD is thought to be 8–9% (www.crohn’s.org.uk).

IRRITABLE BOWEL SYNDROME

Irritable bowel syndrome (IBS) is a common bowel disorder in which the patient complains of abdominal pain and a change in bowel habit. It is the commonest reason for a consultation with the gastroenterologist. The condition may occur following an acute infectious illness, however in the majority of cases no cause is found. On examination, there are no apparent structural abnormalities and the condition does not disturb sleep. Symptoms commonly commence in young adulthood.

Factors that appear to be involved in this condition are:

Treatment is to examine the diet and consider which if any foods exacerbate the symptoms. Some patients find that cutting out dairy products, red meat, fats, coffee and artificial sweeteners substantially reduces the symptoms of IBS. Pharmacological treatment is based on symptom relief (Bruno 2004).

The effect of pregnancy on IBS varies considerably between individuals. Many women find that the abdominal pain and bowel problems worsen during menstruation and also during pregnancy. Others find that IBS completely disappears during pregnancy. IBS has no effect on the pregnancy however, as there has never been any evidence that the absorption of nutrients is affected in IBS.