An estimated 2% of women will undergo non-obstetric-related surgery during pregnancy, which includes appendicitis, cholecystectomy or related to trauma, breast and thyroid disease. This chapter deals only with short term use of analgesics during pregnancy that is associated with management of the pain related to the surgery.

Evidence based on animal research cannot be directly extrapolated to humans, therefore, experimental evidence related to safely of analgesics during pregnancy is scarce. German p 75. While most medications are safe, there are phases of pregnancy that are of particular concern. Teratotoxic risks are highest in the period of organogenesis, days 15 through 60 of pregnancy German, p 75 and just before delivery ANZCA chapter 11.1.1, p 381.

Condition specific perioperative analgesia

Whenever possible, non-pharmacological treatment options should be considered before analgesic medications are used and ongoing analgesic use requires close liaison between the obstetrician and the caregiver managing the pain. ANZCA, chapter 11.1, p 381.

Evidence based recommendations specific to the condition

Recommended treatment options

Non-opioids

Paracetamol in regular adult doses, is the drug of choice during pregnancy German p 75. It is categorized as ‘A’ according to the ADEC drug categorisation for foetal risk ANZCA, see Table 11.1, p 383 and Table 11.2 p 384.

Ibuprofen is the non-specific (ns)-NSAID of choice, due to extensive experience with this medication during pregnancy. German, p 75-76.

Use of NSAIDs during pregnancy is associated with increased risk of miscarriage. ANZCA, chapter 11.1.1, p 381,particularly with long term use. German p 76.

While relatively safe during the first and second trimesters, continuous treatment of none-specific (ns)-NSAIDs during the third trimester should only be given on sound indications. As nsNSAIDs inhibit synthesis of prostaglandins, they may cause premature closure of the fetal ductus arteriosus, fetal renal impairment, inhibition of platelet aggregation and delayed labour and birth. ANZCA, chapter 11.1.1, p 381, German p 76.

Aspirin, category ‘C’ according to the ADEC system. Products containing aspirin should be avoided in the third trimester as it inhibits prostaglandin synthesis and so its effects are similar to nsNSAIDs. In addition aspirin increases bleeding time in newborn and mother. Low dose aspirin (100mg/day) does not affect bleeding time. ANZCA, chapter 11.1.1, p 384.

Coxibs are contraindicated. German p 76-77.

Opioids

Short term use of opioids to treat pain in pregnancy appears to be safe ANZCA, chapter 11.1.1 p 382.

Codeine and dihydrocodeine are category ‘A’ medications. Prolonged, high-dose use prior to delivery may cause withdrawal symptoms in the neonate. ANZCA, Table 11.2, page 384.

Buprenorphine is the opioid of choice because of a low incidence of withdrawal symptoms after long term opioid medication and abundant clinical experience. Tramadol and fentanyl may be used for short of periods of time only. German p 78-80.

Neonatal abstinence syndrome (NAS), requiring treatment occurs in over 60 – 90% of infants exposed to opioids in utero, however, there is no clear relationship between maternal dose and the likelihood or duration of NAS. ANZCA, chapter 11.1.1, p 381-382.

Treatments that are not recommended

Dipyrone is contraindicated in trimesters I and III but can be given in the second trimester if strictly indicated German, p 76.

Ibuprofen, diclofenac and indomethacin are ‘C’ category medications. ANZCA, Table 11.2, page 384.

Hydromorphone, oxycodone and morphine are not recommended, oxycodone is contraindicated German p 78-80

Advice / guidance to patients

Use of medications during pregnancy should be based on published sources and close liaison between the obstetrician and medical practitioner managing the pain. ANZCA, chapter 11.1.1, p 381.

Condition specific issues related to nursing / monitoring patients

Pregnant patients should be excluded from all standard analgesia algorithms and treated individually after consultation with a knowledgeable caregiver.

Summery

When managing the pain of a pregnant patient after non-obstetric related surgery, a second patient, the foetus, should be taken into account.Four major foetal problems must be considered teratogenicity, asphyxia, preterm labour and delivery, and adverse physiologic effects of maternal drugs. Due to the difficulty of conducting large-scale randomized clinical trials in the pregnant population, there insufficient data to allow for specific recommendations. It is important for physicians managing the pain to maintain close liaison with the obstetrician and be guided by published recommendations.

Supplementary reading

1. Kasper EM, Hess PE, Silasi M A pregnant female with a large intracranial mass: Reviewing the evidence to obtain management guidelines for intracranial meningiomas during pregnancy. Surg Neurol Int. 2010 Dec 25;1:95.
2. Reitman E, Flood P. Anaesthetic considerations for non-obstetric surgery during pregnancy. Br J Anaesth. 2011 Dec;107 Suppl 1:i72-8.
3. Wei PL, Keller JJ, Liang HH, Lin HC. Acute appendicitis and adverse pregnancy outcomes: a nationwide population-based study. J Gastrointest Surg. 2012 Jun;16(6):1204-11.