Obstetrics - Investigations Flashcards
Hyperemesis gravidarum ix
• To exclude other aetiologies
o FBCs
o Serum LFTs
o Exclude – abdominal pain, urinary symptoms, infection, drugs, chronic H. Pylori
- Body weight
- Basic metabolic panel – hyponatraemia, hypochloraemia
- Serum U+Es – elevated
• Urinalysis
o Ketonuria
o Elevated specific gravity
• Urine/serum ketones – positive
• Serum TSH + free T4
o Low TSH (due to raised βHCG)
o If TSH is low, order serum-free T4 to exclude hyperthyroidism
o T4 - increased in hyperthyroidism, normal in hyperemesis
• Fetal USS with nuchal translucency
o Increased risk of hyperemesis – Trisomy 21, trisomy 18 (Edwards syndrome), fetal triploidy, multiple gestation, gestational trophoblastic disease, hydrops fetalis
• Serum analytes
o Presence of Trisomy 21, trisomy 18 (Edwards syndrome), fetal triploidy increases the risk of hyperemesis
o Abnormally high or low βhCG + pregnancy have a predictive value for screening in conjunction with nuchal translucency
- H. pylori breath test – in one study, 61.8% of women with hyperemesis were positive for H. Pylori compared to 27.6% without hyperemesis
- PUQE-24 –A scoring system to quantify severity of NVP
Pre-eclampsia ix
• Urinalysis
o If dipstick screening is positive (1+ or more), use albumin:creatinine ratio (8mg/mmol as diagnostic threshold) or protein:creatinine ratio (30mg/mmol as diagnostic threshold) to quantify proteinuria in pregnant women
o Do not use first morning urine void to quantify proteinuria in pregnant women
o Do not use 24hr urine collection
o MC+S if proteinuria is present
• Frequent monitoring of FBC, LFTs, renal function, electrolytes, serum urate
o HELLP syndrome – abnormal LFTs (ALT or AST >70 IU/L), platelet count falling <100x10^9/L
• Clotting studies if there is severe pre-eclampsia or thrombocytopenia
• BP measurement
24-32 weeks – every 3 weeks
32 weeks-delivery – every 2 weeks
Always ask about a) headache and b) epigastric pain each time BP is taken, to be alert for any indication of progression towards eclampsia
• Assessment of fetus – US assessment of fetal growth + the volume of amniotic fluid, Doppler velocimetry of umbilical arteries
o Uterine artery dopplers – predictors of pre-eclampsia development
Bilateral notching
Increased pulsatility index
• PIGF (placental growth factor)-based testing
o To help rule our pre-eclampsia between 20 and up to 35 weeks of pregnancy
o If women with chronic hypertension are suspected of developing pre-eclampsia
Diagnosing pre-eclampsia in women with pre-existing hypertension
• Difficult to diagnose in women with pre-existing hypertension, esp. if there is pre-existing renal disease with proteinuria
• Under these circumstances, pre-eclampsia can present
o In the second half of pregnancy
o Surge in BP or proteinuria
o Other features e.g. thrombocytopenia, increased LFTS, reduced fetal growth
Management of mild-moderate gestational hypertension
What is considered mild/moderate gestational hypertension?
How often should BP be monitored?
What investigations need to be carried out?
How should it be managed?
Mild = 140-149/90-99 Moderate = 150-159/100-109
BP monitoring
1-2/7 until BP is 135/85mmHg or less
Other investigations
• At presentation then weekly – FBC, LFTs, U+Es
• 1-2/7 dipstick proteinuria testing
• PIGF-based testing on 1 occasion if there is suspicion or pre-eclampsia
• Offer fetal heart auscultation at every antenatal appointment
• USS assessment of fetus at dx, If normal repeat every 2-4/52
o USS for fetal growth
o Amniotic fluid volume assessment
o Umbilical artery doppler
o Dipstick, BP measurement
• CTG only if clinically indicated
Management
Do not routinely admit to hospital
Offer pharmacological tx if BP remains >140/90mmHg
Labetalol (alternatives: methyldopa, nifedipine)
Aim for BP of 135/85mmHg or less
Labetalol – 1st line
Nifedipine – 2nd line
Methyldopa – 3rd line
Management of severe gestational hypertension
What is considered severe gestational hypertension?
How often should BP be monitored?
What investigations need to be carried out?
How should it be managed?
Severe = >160/110 or mean arterial pressure <160/110
BP monitoring
Every 15-30 mins until BP is <160/110mmHg
Other investigations
• At presentation then weekly – FBC, LFTs, U+Es (renal function, electrolytes)
• Daily dipstick proteinuria testing while admitted
• PIGF-based testing on 1 occasion if there is suspicion or pre-eclampsia
• Offer fetal heart auscultation at every antenatal appointment
• USS assessment of fetus at dx, If normal repeat every 2/52 if severe htn persists
o USS for fetal growth
o Amniotic fluid volume assessment
o Umbilical artery doppler
• CTG at dx and then only if clinically indicated
Management
Admit, but if BP falls below 160/110 mmHg manage as for HTN
Offer pharmacological tx to all women
Labetalol (alternatives: methyldopa, nifedipine)
Aim for BP of 135/85 mmHg or less
Labetalol – 1st line
Nifedipine – 2nd line
Methyldopa – 3rd line
Amniotic fluid embolus investigations
• CXR o Pulmonary oedema o ARDS o Right atrial enlargement o Prominent pulmonary artery
• ECG
o Right heart strain
o Arrhythmia
• Echo
o High filling pressures are indicative of a failing ventricle
- ABG – determine the degree of hypoxaemia
- Clotting screen – very abnormal, even before any observable haemorrhage
• Post-mortem
o Fetal squamous cells + hair (lanugo) in the maternal pulmonary circulation
Diabetes in pregnancy
Investigations in the first antenatal clinic appointment – 10 weeks
Retinal assessment
Renal assessment
Measurement of HbA1c levels to determine the level of risk for the pregnancy
Self-monitoring of blood glucose or OGTT asap for women with previous gestational diabetes
Confirm the viability of the pregnancy + gestational age t 7-9 weeks
Diabetes in pregnancy
Investigations in 2nd + 3rd trimester
HbA1c to assess level of risk for the pregnancy
Diabetes in pregnancy
Investigations during the 16-20 weeks
Retinal assessment if diabetic retinopathy is present
20 weeks
Anomaly scans incl. examination of the fetal heart
Pre-existing Diabetes + gestational diabetes (GDM) in pregnancy
Investigations on the 28, 32, 36 weeks
serial growth scans
28 Foetal surveillance, retinal assessment
• OGTT if risk factors present now and no Hx of previous gestational diabetes
32 Foetal surveillance
36 Foetal surveillance
Foetal surveillance = fetal growth + amniotic fluid volume
Diabetes in pregnancy
Investigations on the 38th week
Offer tests for fetal wellbeing
Offer these tests before 38 weeks - Routine monitoring of foetal wellbeing if there is risk of foetal growth restriction
Fetal umbilical artery doppler recording
Fetal heart rate recording
Biophysical profile testing
Diabetes in pregnancy
Investigations 6-13 weeks post partum
Fasting plasma glucose to exclude diabetes
<6.0mmol/L low probability of diabetes, need an annual test, moderate risk of developing T2DM
6.0-6.9mmol/L high risk of T2DM
> 7.0mmol/L 50% chance of having/developing T2DM offer diagnostic test to confirm
What does the combined screening test test for?
When should it be done?
What are the 3 components?
Combined test
Tests for T13 (Patau’s syndrome), T18 (Edward’s syndrome), T21 (Down’s syndrome)
Positive combined test can be due to T13, T18, T21
- The combined test is testing for 2 serological markers (hCG + PAPP-A) + 1 radiological marker (nuchal translucency)
- Should be done bn 11-13+6 weeks
The differentiating test tends to be PAPP-A – it is even lower than that which would be expected in Down’s syndrome
What findings would you expect to find in a positive combined test?
What do the results indicate?
Raised bHCG
Low PAPP-A
Thickened nuchal translucency
Positive combined test can be due to T13, T18, T21
Which part of the combined test can differentiate between T13 (Patau syndrome), T18 (Edward’s syndrome) and T21 (Down’s syndrome)?
PAPP-A is very low in trisomy 18 and 13, compared to trisomy 21
What is the triple test in pre-natal screening?
What is the quadruple test in pre-natal screening?
When does this testing take place?
Tripe test = alpha-fetoprotein, unconjugated oestriol, hCG
Quadruple test = alpha-fetoprotein, unconjugated oestriol, hCG, inhibin-A
• If women book later in pregnancy, either the triple or quadruple test is offered between 15-20 weeks
What is alfa fetoprotein?
What is inhibin A?
Alfa-fetoprotein • Part of the triple + quadruple test • Produced by fetal yolk sac + liver • Does not test for T13 • Low in Down’s syndrome + T18 • Not part of the combined test
Inhibin A • Part of the quadruple test • produced by the placenta • Variable in trisomy 13 • Unchanged in trisomy 18 • High in Down’s syndrome • Not part of the combined test
What is Terbutaline and where is it used?
Terbutaline – tocolytic from the betamimetic class of drugs – acts to prevent + slow uterine contractions in preterm labour
Gestational diabetes melitus GDM ix
• Offer women who have had GDM in previous pregnancy
o Early self-monitoring of blood glucose
o 2h OGTT asap after booking + 2h OGTT at 24-28 weeks if first OGTT is normal
Offer women with a RF for GDM* an OGTT at 24-28w
(because this is where GDM usually appears)
• Screening should be offered at booking to women with the following RF*
o BMI > 30kg/m2
o Previous macrosomic baby >4.5kg
o Previous GDM
o First-degree relative with diabetes
o Family origin with a high prevalence of diabetes (South Asian, black Caribbean, Middle Eastern)
• WHO recommends that HbA1c can be used as a diagnostic test for diabetes
o However it is currently not recommended for diagnosis during pregnancy
o Can be used to assess level of risk to the pregnancy (NICE)
NICE
• Fasting plasma glucose, random blood glucose, HbA1c, glucose challenge test, urinalysis for glucose should not be used to assess risk of developing GDM
• Glycosuria 2+ on one occasion or 1+ on two or more occasions - ?undiagnosed GDM – consider further testing to exclude GDM
Ectopic pregnancy investigations
- Pregnancy test
- TVUSS – 1st line
Definite - Adnexal mass that moves separate to the ovary, comprising a gestational sac containing a yolk sac or
An adnexal mass, moving separately to the ovary, comprising a gestational sac and fetal pole (+/- fetal heartbeat)
High probability - An adnexal mass moving separately to the ovary, with an empty gestational sac (sometimes described as a “tubal ring” or “bagel sign”, “blob sign”) or
A complex, inhomogeneous adnexal mass, moving separate to the ovary
Possible - Empty uterus or
A collection of fluid within the uterine cavity (sometimes described as a pseudo-sac)
- Abdominal USS for women with an enlarged uterus or other pelvic pathology (e.g. fibroids, ovarian cyst)
- MRI – 2nd line
• Pregnancy of unknown location/PUL + woman is stable - hCG levels (taken 48h apart)
However, clinical symptoms > hCG levels
if serum Hcg levels decrease >50% after 48h – inform woman that her pregnancy is unlikely to continue but this is not confirmed - expectant management + pregnancy test 14 days after the second serum hcg – if positive, return to the early pregnancy assessment service for clinical review within 24h
if there is a change in hCG concentration between 50% decline and 63% rise over 48 hours, then the woman should be referred for clinical review in an early pregnancy assessment service within 24h
if there is an increase in serum hCG levels >63% after 48 hours – likely to be developing an intrauterine pregnancy. Scan to determine the location of the pregnancy between 7 and 14 days later
[• Normal pregnancy – hCG doubles every 48 hours
• Miscarriage – hCG decreases
• Ectopic – hCG hovers around a single value]
• Do not perform an internal examination if you suspect an ectopic
o Risk of rupture during palpation
Referral to hospital for urgent assessment via the early pregnancy assessment service or on-call gynaecologist out of hours • Pain + abdominal tenderness • Pelvic tenderness • Cervical motion tenderness • Vaginal bleeding
TVUSS findings for
o Cervical ectopic pregnancies
o Interstitial pregnancy
o Cornual pregnancy
o Heterotopic pregnancy
o Cervical ectopic pregnancies
Empty uterus
Barrel shaped cervix
Gestational sac present below the level of the internal cervical os
Absence of the sliding sign (negative sliding sign)
Blood flow around the gestational sac using colour Doppler
o Interstitial pregnancy
Empty uterine cavity
Products of conception/gestational sac located laterally in the interstitial (intramural) part of the tube + surrounded by less than 5mm of myometrium in all imaging planes
Presence of the interstitial line sign
Sonographic findings in 2D can be further confirmed using 3D USS to avoid misdiagnosis with early intrauterine or angular (implantation in the lateral angles of the uterine cavity) pregnancy
o Cornual pregnancy
Visualisation of a single interstitial portion of fallopian tube in the main uterine body
Gestational sac/products of conception seen mobile and separate from the uterus and completely surrounded by myometrium
Vascular pedicle adjoining the gestational sac to the unicornuate uterus
o Heterotopic pregnancy
USS findings demonstrate an intrauterine pregnancy and a coexisting ectopic pregnancy
Investigations of placenta praevia
- Vaginal bleeding after 20 weeks of gestation - High clinical suspicion
- Never do a bimanual
• USS
o 20 weeks scan should include placental localisation
Praevia = covering the os, low lying = <20mm from internal os
o 32 weeks - Follow up USS examination incl. TVUSS - to diagnose persistent low-lying placenta and/or placenta praevia
Cannot exclude a placental abruption which is a clinical dx
If still low-lying/praevia at 32 weeks (grade I/II) - rescan at 36 weeks
If still present + grade III/IV – admit at 34 weeks – CS at 37 weeks (alistair)
Grade I (vaginal delivery) (alistair)
Still low lying or Grade III/IV (CS at 37 weeks – before allowing for spontaneous labour to occur) (alistair) (specialties guide)
o Cervical length measurement to facilitate management decisions in asymptomatic women with placenta praevia
Short cervical length on TVS before 34 weeks of gestation - increased risk of pre-term emergency delivery + massive haemorrhage at C-section
• Other ix – depend on the context
o FBC, group and cross-match, clotting studies, U+Es, LFTs, fetal monitoring, Kleihauer test, CTG
• Scans – CTG if >27 weeks, umbilical artery doppler every 2 weeks, growth scans
Vasa praevia ix
• USS at the time of the routine fetal anomaly scan
o High diagnostic accuracy
• Transvaginal colour doppler US + transabdominal colour Doppler US
o Best diagnostic accuracy
• It is essential to confirm the presence of vasa praevia by US in the third trimester
o To avoid unnecessary anxiety/admissions/prematurity/C-section
- Kleinhauer test
- Haemoglobin electrophoresis – identify if foetal or maternal blood (takes a long time)
- Doppler USS
Placental abruption ix
- Clinical dx, no sensitive/reliable diagnostic tests available
- Tense (hypertonic), tender, “woody” feel uterus
- Vaginal exam – cervical dilation (do not do a vaginal exam in praevia, if unsure, do not do bimanual!)
- USS – not reliable as blood clot is not easily distinguishable from the placenta, do it to exclude Placental praevia
- CTG – HR abnormalities due to fetal hypoxia due to abruption
• Plt count – low
o Low platelet counts may indicate a consumptive process seen in relation to significant abruption
o This may be associated with coagulopathy
• BP – may be normal, even with massive haemorrhage, as fit healthy women can tolerate significant loss prior to showing signs of decompensation
• Serial USS for fetal growth after episode of APH until term
o Increased risk of adverse perinatal outcomes incl. small for gestational age fetus, FGR (fetal growth restriction)
- Kleihauer test
- Bloods – FBC, clotting studies, G+S, U+E X-match
Which investigations are important after an episode of APH?
• Weekly Serial USS for fetal growth after episode of APH until term
o Increased risk of adverse perinatal outcomes incl. small for gestational age fetus, FGR (fetal growth restriction)
Monitoring plasma levels of AEDs during pregnancy
o Routine monitoring of AED levels in pregnancy is not recommended
o AED conc. In plasma can change during pregnancy
o Doses of phenytoin, carbamazepine, lamotrigine should be adjusted on the basis of plasma-drug conc. Monitoring
o If seizures increase or are likely to increase, monitoring for AED levels may be useful when making dose adjustments (particularly levels of lamotrigine + phenytoin which may be particularly affected in pregnancy)
Monitoring of pregnant women on AEDs
o 18-20+6 weeks neural tube defects, major cardiac defects, structural anomalies
o 11-13 weeks scanning may allow major malformations to be detected sooner
o Serial growth scans every 4 weeks from 28-36 weeks gestation for detection of SGA + to plan further management
o Topiramate or levetiracetam monitor fetal growth
UTI ix
• Urinalysis – performed at every antenatal visit
• Urine MC+S – MSU sent at booking visit (ideally <10w) as screening test
o Presence of bacteria
o Protein – renal disease, pre-eclampsia
o Persistent glycosuria – T1DM, T2DM, GDM
o Nitrites (UTIs)
Which pregnant women will need TFTs ?
At booking • Current thyroid disease • Previous thyroid disease • 1st degree FHx thyroid disease • AI conditions (Coeliac, T1/T2DM, GDM)
Women with HG
Hyperthyroidism during pregnancy can present as hyperemesis gravidarum or as a thyroid storm – always check the TFTs
Hyperemesis gravidarum is associated with abnormal TFTs which improve once it settles
HG:
o Decreased TSH (due to increased βHCG)
o If TSH is low, order serum-free T4 to exclude hyperthyroidism
o T4 - high in hyperthyroidism, normal in hyperemesis
Thyroid disease in pregnancy ix
- TSH should be measured every 4-6 weeks in pregnant patients
- Hyperemesis gravidarum is associated with abnormal TFTs which improve once it settles (low TSH, normal T4)
• Postpartum
o Serum TSH should be checked 6 after weeks delivery
o Once stable, TSH should be measured at least annually
• PPT (post-partum thyroiditis)
o Positive for TPO antibodies
o Normal ESR
Hyperthyroidism in pregnancy - monitoring
o TFTs every 2 weeks until the patent is stable on medication
o Then weekly after 32-24 weeks of gestation in those with poorly controlled hyperthyroidism
o Serial fetal US – IUGR, hydrops fetalis, advanced bone age, goitre, tachycardia, HF
o Check TRAb at the end of the second trimester
`Cardiac disorders in pregnancy ix
• Echo – usually performed at booking + at 28 weeks
Puerperal cardiomyopathy + myositis/ Peripartum cardiomyopathy ix
o ECG – LVH
o CXR – cardiomegaly
o Echo – recent left ventricular dysfunction
o MRI – safe + non-invasive, can help with dx + prognosis
o Endometrial biopsy – in cases of diagnostic difficulty
