Appendicitis in Pregnancy

Why this one is genuinely difficult

Appendicitis is the commonest reason for non-obstetric abdominal surgery during pregnancy, and it is also the diagnosis most often delayed. NICE Clinical Knowledge Summaries states the problem directly: "Appendicitis may present atypically, particularly in the very young, elderly, and in pregnancy, and the anatomical position of the appendix may vary, resulting in different clinical presentations."

Three things conspire. The growing uterus pushes the appendix upwards and outwards, so the pain may not be in the classic spot in the right lower abdomen. Nausea, vomiting and loss of appetite are common in pregnancy anyway, so the usual warning signs blend into the background. And the white cell count rises normally in pregnancy, so a raised result loses much of its diagnostic value.

The result is that appendicitis in pregnancy is often diagnosed later than it would be otherwise, and later diagnosis means a higher chance of the appendix perforating.

What it feels like, and how that changes with gestation

The NHS describes appendicitis as typically starting with "pain in the middle of your tummy that may come and go", which within hours "travels to your lower right-hand side, where the appendix usually lies, and becomes constant and severe". Pressing on the area, coughing or walking may make it worse.

In pregnancy, that endpoint moves. In the first trimester the pain is often in the usual place. As the uterus enlarges through the second and third trimesters, the appendix is displaced upwards, so pain may be felt higher in the right abdomen, sometimes near the right flank or under the ribs. That is one reason appendicitis gets mistaken for a kidney infection, gallbladder pain or even labour.

Other features NICE CKS lists include "abdominal distension, guarding, rebound tenderness or percussion tenderness, or absent bowel sounds (which may all suggest peritonitis)" and "a palpable abdominal mass (which may suggest an appendix mass or abscess)". Guarding is harder to detect through a pregnant abdomen, which is another part of the difficulty.

What happens when you present

NICE CKS is unambiguous about the pathway for suspected appendicitis: "Emergency admission for specialist assessment and management, such as further imaging and non-operative (antibiotics) or operative management (appendicectomy or percutaneous drainage of appendix abscess, for example)."

In pregnancy that assessment is joint. You will usually be seen by both a surgical team and an obstetric team, because the differential includes conditions each specialty owns. Placental abruption, red degeneration of a fibroid, ovarian torsion, a urinary or kidney infection, and severe pre-eclampsia can all produce abdominal pain that overlaps.

Expect blood tests, urine testing and observations, and expect to be watched over hours rather than sent home quickly. Serial examination is one of the main tools when imaging is equivocal.

Imaging, and what is safe

Ultrasound is the first-line imaging test in pregnancy because it involves no ionising radiation. Its weakness is that the appendix is often not visualised at all, particularly later in pregnancy, and a scan that does not see the appendix does not exclude appendicitis.

Where ultrasound is inconclusive, MRI is the next step, and it likewise uses no ionising radiation. NICE guidance in adjacent areas follows the same logic — CG188 on gallstone disease escalates from ultrasound to MRCP rather than to CT.

CT scanning does involve radiation and is generally avoided in pregnancy, though it is used where the alternative is a dangerous delay. If CT is proposed, ask what the alternative would be and how quickly it could happen; the answer is sometimes that MRI is not available out of hours.

Surgery, and why it is not postponed

Where appendicitis is diagnosed, an operation is generally done rather than deferred. Laparoscopic appendicectomy is performed in pregnancy, including in the second and third trimesters in experienced hands, and an open operation is an alternative depending on gestation and local practice.

The reason for not waiting is that a perforated appendix is far more dangerous to a pregnancy than an operation is. Perforation carries a substantially higher risk of preterm birth and of pregnancy loss than a straightforward appendicectomy.

Anaesthesia in pregnancy is routine and safe when managed by an obstetric-aware team. Depending on gestation, you may have fetal heart monitoring before and after the operation, and steroids may be given if there is a realistic chance of preterm birth. Ask what the plan is for your gestation.

What to do about pain you are unsure about

The NHS advice is to call 999 or attend an emergency department if the pain "suddenly gets worse and spreads across your tummy", because this can mean the appendix has burst. Otherwise, seek urgent advice for abdominal pain that is getting steadily worse over hours, particularly with a temperature, vomiting, or pain that stops you moving normally.

Say you are pregnant and how many weeks at first contact, including at reception. It changes the triage category and it changes which team assesses you. If you have already been assessed and sent home but the pain is worsening, go back — appendicitis evolves, and a normal examination three hours ago does not describe now.

Your routine antenatal care under NICE guideline NG201 continues throughout, and any abdominal event in pregnancy is worth having recorded in your notes for later reference.

After the operation

Recovery from a laparoscopic appendicectomy in pregnancy is broadly similar to recovery outside it, with the addition of obstetric observation. Expect pain relief that is chosen with pregnancy in mind, early mobilisation to reduce the risk of blood clots, and usually assessment for whether blood-clot prevention measures are needed, because pregnancy and surgery each raise that risk on their own.

Contractions in the days after abdominal surgery are common and usually settle. Report them anyway, along with any bleeding, fluid loss or change in fetal movements, so that preterm labour is excluded rather than assumed away.

Where the appendix had perforated, expect a longer course of antibiotics, a longer stay and closer monitoring of the pregnancy afterwards. Ask before discharge what follow-up is planned, whether a growth scan has been added, and who to contact if the pain returns.