Pain Management for the Pregnant Patient
Obstetrics and Gynecology
Pregnant patients may present to emergency with new or exacerbations of chronic pain. Commonly this can include lower back pain (LBP), pelvic girdle pain (PGP), and abdominal pain.
- Effects on the pregnancy and fetus need to be considered when deciding on an analgesic.
- There are some important diagnostic considerations in a pregnant patient presenting with abdominal pain.
ABDOMINAL PAIN CONSIDERATIONS
- Characterize pain.
- Current pregnancy history (dates, ultrasounds, complications).
- Vaginal bleeding, or leaking fluid.
- Fetal movements (in later half of pregnancy).
- Past OB history (eg. Preeclampsia, previous C-section).
- Vital signs including blood pressure.
- Examine abdomen.
- SFH, fetal HR, cardiotocography if considering contractions, sterile pelvic exam if indicated.
- Main imaging modality used is abdomen/pelvic US.
- Transvaginal US useful especially for early pregnancy.
- Beta-hCG, CBC, type, and screen if vaginal bleeding.
- Consider LFT, kidney function, urine dip.
Some considerations for differential for abdominal pain during pregnancy
- Miscarriage: often the first trimester, can be vaginal bleeding, see PEC summary “1st Trimester Bleeding: Miscarriage”.
- Ectopic Pregnancy: often presents as first trimester abdominal/pelvic pain, can be vaginal bleeding, see PEC summary “1st Trimester Bleeding: Ectopic Pregnancy”.
- Placental Abruption: can present with abdominal pain, vaginal bleeding, uterine tenderness.
- Uterine Rupture: at risk if previous C-section or recent abdominal trauma, can present with abdominal pain, bleeding, peritoneal signs, abnormal FHR, urgent intervention required.
- Labor: Uterine contractions increasing in frequency & intensity with cervix changes, patient may note gush of fluid or small amount of blood.
- Intra-amniotic infection: fever, abdominal pain, leukocytosis, tender uterus.
LIVER DISEASE SPECTRUM (USUALLY LATER)
- Acute Fatty Liver: nausea, vomiting, abnormal LFTs, may have abdominal pain.
- Pre-eclampsia: new-onset HTN, proteinuria/decreased kidney function, may have abdominal pain.
- HELLP: abnormal LFTs, low platelets, hemolysis on blood smear, often presents with abdominal pain & can be associated with risk of hepatic rupture.
Also consider regular differential for abdominal pain such as obstruction / appendicitis / gall stones / kidney stones / pyelonephritis / UTI / ovarian torsion / ovarian cyst rupture / etc.
Common benign causes include round ligament pain earlier in pregnancy and fetal movements later in pregnancy.
- Lifestyle modifications such as exercise (especially helpful for back pain).
- Specific supports/braces (eg. Pelvic belts for pelvic girdle pain).
Pharmacologic (Lowest dose for shortest duration)
- Generally first line.
- Not associated with any major congenital malformations or fetal death2 .
- Some studies suggesting association with childhood ADHD & asthma -> reviews of studies note many confounding variables with no definitive causal link1,2,4.
- Max 1g q6hrs (max 4g in 24hrs)2 .
- Safety depends on timing in pregnancy.
- Inconsistent evidence for association with 1st trimester miscarriage. Where associations are seen, tend to be more with diclofenac & indomethacin rather than ibuprofen2 .
- No significant evidence to support NSAIDs cause congenital malformations2.
- Between 20-30 weeks NSAIDs should be avoided and are contraindicated 30+ weeks due to risk of oligohydramnios/kidney injury and premature ductus arteriosus closure1,2,5.
- Short course of opioids can be used for moderate-severe pain that is not responsive to non-pharmacologic options or acetaminophen (eg. Morphine)1,2,4 .
- Recommend consulting obstetrics provider.
- Case reports of neural tube and heart defects following opioid use in early pregnancy reported by the FDA as a possible risk, but limited evidence1,2,4.
- Use later in pregnancy has risk for neonatal respiratory depression.
- Prolonged use in pregnancy can result in neonatal abstinence syndrome – resulting in some problems with feeding, sleeping, temperature regulation.
- Severe neonatal abstinence syndrome can cause neonatal respiratory distress, seizures, failure to thrive, developmental delay, and may require a morphine taper after birth.
Quality Of Evidence?
We are highly confident that the true effect lies close to that of the estimate of the effect. There is a wide range of studies included in the analyses with no major limitations, there is little variation between studies, and the summary estimate has a narrow confidence interval.
We consider that the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. There are only a few studies and some have limitations but not major flaws, there are some variations between studies, or the confidence interval of the summary estimate is wide.
When the true effect may be substantially different from the estimate of the effect. The studies have major flaws, there is important variations between studies, of the confidence interval of the summary estimate is very wide.
NSAIDs should be avoided in late pregnancy and are contraindicated beyond 30 weeks.
Moderate quality evidence – Recent review notes consistent results shown in few observational studies and supported by numerous case reports to FDA. However, studies are limited by participant numbers and design.2,5
Patient information on back and pelvic pain:
The purpose of this document is to provide health care professionals with key facts and recommendations for the diagnosis and treatment of patients in the emergency department. This summary was produced by the BC Emergency Medicine Network and uses the best available knowledge at the time of publication. However, healthcare professionals should continue to use their own judgment and take into consideration context, resources and other relevant factors. The BC Emergency Medicine Network is not liable for any damages, claims, liabilities, costs or obligations arising from the use of this document including loss or damages arising from any claims made by a third party. The BC Emergency Medicine Network also assumes no responsibility or liability for changes made to this document without its consent.
Last Updated Jan 19, 2022
Visit our website at https://www.bcemergencynetwork.ca
Add public comment…