Nuchal Translucency (NT) Scan – Short Notes

• Performed at 11-13+6 weeks gestation, when fetal crown-rump length (CRL) is 45-84 mm.
• Midsagittal section of the fetus, neck in neutral position, image magnified so head/neck/upper thorax fill most of the screen.
• Calipers placed "on-to-on" on the inner borders of the nuchal line (measuring the maximum thickness of the translucency, not the nuchal skin fold).
• Must distinguish NT from the amnion (a false membrane can mimic the NT edge).

• Used as part of first-trimester aneuploidy screening, typically combined with maternal serum analytes (free beta-hCG and PAPP-A) plus maternal age -> patient-specific risk for trisomy 21, 18, 13.
• NT and PAPP-A are the most efficient individual markers between 9-12 weeks; combined screening performs best around 11 weeks.

• At a 5% screen-positive rate: Down syndrome detection rate ~88% (95% CI 84-89.4%).
• In women >35 years: 90-92% detection with 16-22% false-positive rate.

• 90% of trisomy 18 pregnancies are screen-positive with combined NT + biochemical screening.

• Chromosomal aneuploidy - trisomy 21, 18, 13, monosomy X (Turner syndrome, often with cystic hygroma), triploidy.
• Structural anomalies, especially congenital cardiac defects - NT screening at 10-14 weeks has been used to flag major cardiac defects even with a normal karyotype.
• Skeletal dysplasias, diaphragmatic hernia, abdominal wall defects.
• Genetic syndromes / RASopathies (e.g., Noonan syndrome) - additional testing (microarray, RASopathy panel, exome sequencing) is recommended when karyotype is normal but NT remains elevated.
• Adverse pregnancy outcome even when karyotype and anatomy are normal - larger NT correlates with higher risk of miscarriage/fetal loss.

• Absent or hypoplastic NB increases suspicion for trisomy 21 (absent in ~60-70% of Down syndrome fetuses at 11-13 weeks vs a small percentage of euploid fetuses).
• Reflects the flat nasal bridge phenotype of Down syndrome.

1. Genetic counseling.
2. Consider microarray / expanded genetic testing (cell-free DNA can be falsely reassuring if a structural defect is present).
3. Detailed fetal anatomy scan and fetal echocardiography later in pregnancy (18-22 weeks) to look for structural anomalies not evident in the first trimester.
4. Serial growth and anatomy surveillance given increased risk of adverse outcome even if initial workup is normal.

• NT alone is a screening tool, not diagnostic - an elevated NT raises risk but does not confirm a chromosomal or structural abnormality.
• Quality matters: measurement technique is operator-dependent; ongoing epidemiologic monitoring of individual sonographer/sonologist performance (rather than ad hoc image review) is the preferred quality-control method - Tietz Textbook of Laboratory Medicine.

Figure: Midsagittal view of a 12-week fetus demonstrating the NT (measured between yellow dots) and the amnion.

• PMID 40519157 (2025) - outcomes of fetuses with early increased NT: systematic review/meta-analysis, reinforcing that increased NT carries risk beyond aneuploidy alone.
• PMID 37019452 (2023) - whole exome sequencing in fetuses with isolated increased NT and normal karyotype: meta-analysis supports added diagnostic yield of exome sequencing, consistent with the textbook recommendation above.
• PMID 40190084 (2025) - explores link between cystic hygroma/NT and congenital heart disease/lymphatic abnormalities.

Verbal Autopsy - Short Notes

• In most low- and middle-income countries (LMICs), civil (vital) registration systems are incomplete, so most deaths occur without a physician-certified cause of death.
• VA fills this gap by systematically collecting information (structured questionnaire) from next-of-kin about the terminal illness/event, which is then reviewed (by physicians or algorithm/computer-coded methods) to assign a probable cause of death, usually coded to ICD-10.

• Standardized questionnaires (e.g., WHO Verbal Autopsy Standard instrument) are administered to relatives soon after a death.
• Records of births and deaths are collected periodically among defined populations under demographic surveillance systems run by research institutions in developing countries.
• Cause-of-death assignment can be done by physician review or by automated algorithms (e.g., InterVA, SmartVA) that map reported symptoms to probable causes.

1. Maternal mortality measurement - One of the recognized approaches for estimating maternal mortality ratio (MMR) where civil registration is absent, alongside household surveys, sisterhood method, RAMOS (Reproductive Age Mortality Studies), and census methods - Park's PSM, p. 649-650.
2. India - SRS/RHIME - India's Sample Registration System (SRS) uses an enhanced form of verbal autopsy called RHIME (Representative, Re-sampled, Routine Household Interview of Mortality with Medical Evaluation), introduced from 2000 onward as part of a prospective study of ~1 million deaths. RHIME includes random re-sampling of fieldwork by an independent team to maintain data quality, and causes are coded per WHO Global Burden of Disease categories (haemorrhage, sepsis, hypertensive disorders, obstructed labour, abortion, other) - Park's PSM, p. 651.
3. Global Burden of Disease (GBD) studies - GBD estimates (e.g., GBD 2019) combine vital registration, country-level surveillance, disease registries, and verbal autopsy data to model cause-specific mortality worldwide - Fuster and Hurst's The Heart, 15th ed.
4. Cardiovascular disease/stroke burden estimation - In regions with scarce vital registration, VA surveys have been used to estimate CVD burden, e.g., 9-13% of deaths attributable to CVD (especially stroke) in some low-resource settings - Fuster and Hurst's The Heart, 15th ed.
5. Psychiatric epidemiology - VA has revealed underestimation of suicide by official statistics; a VA study in South India found suicide rates roughly 10-fold higher than official national estimates - Kaplan and Sadock's Synopsis of Psychiatry.
6. Standardization - "Verbal autopsy standards" exist for ascertaining and attributing causes of death, listed alongside other health classification systems (ICD, ATC/DDD, ICNP) - Kaplan & Sadock's Comprehensive Textbook of Psychiatry.
7. Forensic/COVID-19 context - WHO-recommended protocols for COVID-19 deaths include general/external examination plus verbal autopsy, alongside criteria of elimination and exclusion, when standard postmortem examination is limited - The Essentials of Forensic Medicine and Toxicology, 36th ed.

• Only feasible method for cause-of-death data in areas lacking vital registration or medical certification.
• Useful for community-based, longitudinal demographic surveillance (e.g., HDSS sites) and large national mortality surveys (SRS-India).
• Can capture socially sensitive causes (e.g., suicide, maternal deaths) that are under-reported in official records.

• Relies on recall and lay knowledge of the informant, subject to recall bias and misclassification.
• Less accurate for causes with overlapping/nonspecific symptoms (e.g., differentiating some cardiovascular vs. respiratory causes).
• Physician-coded VA can have inter-rater variability; algorithmic methods depend on validation against gold-standard (hospital-certified) causes.

• PMID 39030612 (2024) - systematic review validating malaria-attributed deaths using VA studies, highlighting ongoing efforts to improve VA accuracy for specific causes.
• PMID 37638359 (2023) - systematic review of CVD mortality based on VA in LMICs (Bulletin of WHO), consistent with the textbook's use of VA for CVD/stroke burden estimation.
• PMID 36640854 (2023) - systematic review of global autopsy rates in all-cause and sudden death, contextualizing the gap that VA and other methods aim to fill where formal autopsy rates are low.

Verbal Autopsy - Short Notes (MS OBG Perspective)

1. Civil registration systems
2. Household surveys
3. Sisterhood method (direct/indirect) - interviews respondents about survival of adult sisters
4. RAMOS (Reproductive Age Mortality Studies) - investigates all deaths in women of reproductive age using multiple data sources
5. Verbal autopsy
6. Census (with added questions)

• India's Sample Registration System (SRS) uses RHIME (Representative, Re-sampled, Routine Household Interview of Mortality with Medical Evaluation) - an enhanced verbal autopsy tool.
• Started from year 2000, part of a prospective study covering ~1 million deaths.
• Includes random re-sampling of fieldwork by an independent team for quality control.
• Deaths are coded using WHO Global Burden of Disease categories with ICD-10 codes: haemorrhage, sepsis, hypertensive disorders, obstructed labour, abortion, and other causes.
• This is how India generates nationally representative cause-specific MMR data (EAG states vs southern states vs other states comparison) despite incomplete civil registration in many regions.

• Trained field investigator interviews family/attendants soon after death using a structured questionnaire (symptoms, sequence of events, treatment sought, delays).
• Data reviewed/coded by physicians or algorithm (e.g., WHO VA instrument) to assign probable cause of death.

• Ties into the "Three Delays Model" (delay in decision to seek care, delay in reaching facility, delay in receiving care) often explored through VA narratives.
• Complements Confidential Enquiry into Maternal Deaths and facility-based maternal death review (MDR) - VA specifically covers deaths that never reach a facility.
• Contributes to India's major causes of maternal death list: haemorrhage, sepsis, abortion-related complications, hypertensive disorders, obstructed labour, anaemia (indirect cause) - Park's PSM, p. 651.

• Only feasible method in areas without complete civil registration.
• Captures home deaths and community-level cause-of-death patterns missed by hospital data.
• Useful for large-scale surveillance (SRS/RHIME model, HDSS sites).

• Recall bias / informant may not know exact clinical details.
• Cannot always distinguish between clinically similar causes (e.g., eclampsia vs other hypertensive crisis).
• Coding variability between physician reviewers; requires trained interviewers and standardized instruments.
• Cannot substitute for facility-based clinical/laboratory diagnosis.

Labour Analgesia - Short Notes (MS OBG)

• First stage (uterine contractions + cervical dilatation): visceral pain via sympathetic afferents entering the spinal cord at T10-L1.
• Second stage (perineal stretching, descent of the head): somatic pain via the pudendal nerve (S2-S4).
• This dermatomal basis explains why a lumbar epidural covering T10-S4 is needed for complete labour analgesia through delivery.

• Psychoprophylaxis (Lamaze technique), breathing exercises, relaxation
• Continuous labour support / doula
• Hydrotherapy (warm water immersion)
• TENS (transcutaneous electrical nerve stimulation)
• Sterile water injections, acupuncture, hypnosis, aromatherapy
• Ambulation and position changes

• Parenteral opioids: pethidine (meperidine), fentanyl, remifentanil (PCA)
• Inhalational analgesia: nitrous oxide (Entonox, 50:50 N2O/O2)
• Note: remifentanil PCA is inferior to neuraxial labour analgesia per meta-analyses - Miller's Anesthesia, 10e.

• Epidural analgesia - most common and effective; lumbar epidural is the "mainstay of labour analgesia" - Miller's Anesthesia, 10e.
• Combined spinal-epidural (CSE)
• Dural puncture epidural (DPE) - newer technique
• Continuous spinal analgesia
• Programmed intermittent epidural bolus (PIEB) - most effective current technique for labour pain relief along with continuous epidural infusion - Morgan and Mikhail's Clinical Anesthesiology, 7e.
• Pudendal nerve block - for second stage/instrumental delivery
• Paracervical block - rarely used now (risk of fetal bradycardia)

• Drugs: bupivacaine or ropivacaine (low-dose) combined with an opioid (fentanyl/sufentanil) - "walking epidural" - provides excellent analgesia with reduced motor blockade.
• Can be initiated in early labour after obstetric evaluation; timing of initiation (early vs late) does not affect length of labour or mode of delivery (Chestnut et al., cited in Creasy & Resnik's Maternal-Fetal Medicine).
• Provides pain relief for first and second stages without altering maternal consciousness.

• Large natural-experiment data (Zhang et al.) showed epidural analgesia does not increase overall cesarean delivery rate, oxytocin use, or instrumental delivery rate.
• The only consistent effect is prolongation of the second stage of labour (mean ~25 minutes).
• Fear of dystocia/cesarean should not be used to withhold epidural analgesia - Creasy & Resnik's Maternal-Fetal Medicine, p. 968.

• Maternal hypotension (due to sympathetic blockade) - managed with IV prehydration and avoiding supine position (left lateral tilt).
• Late fetal heart rate decelerations from decreased uteroplacental perfusion (more common with bupivacaine than chloroprocaine/lidocaine) - up to 20% of cases.
• Uterine hypertonus with oxytocin augmentation can worsen uteroplacental insufficiency (FHR abnormalities in up to 70% in that setting).
• Post-dural puncture headache (with inadvertent dural puncture).
• Chronic backache - earlier retrospective studies suggested association, but prospective 1-year follow-up studies found no significant difference in persistent back pain between epidural and non-epidural groups.
• Maternal fever, pruritus (with opioids), rare: high spinal block, local anesthetic systemic toxicity, epidural hematoma/abscess.

• Absolute: patient refusal, coagulopathy/anticoagulation, local infection at insertion site, raised ICP, uncorrected hypovolemia/shock.
• Relative: severe cardiac lesions with fixed cardiac output, spinal deformity, sepsis.

• Superior pain relief, doesn't cause maternal/fetal respiratory depression (unlike opioids), maintains maternal alertness, provides ready anesthesia if operative delivery needed.

• Epidural analgesia does not increase rate of operative delivery per current evidence (Morgan & Mikhail, 7e) - contrasts with older teaching.
• Vacuum extraction requires less anesthesia than forceps delivery, relevant when comparing analgesia needs for assisted deliveries.

• PMID 40121178 (2025, Br J Anaesth) - meta-analysis comparing epidural vs dural puncture epidural (DPE) analgesia in labouring women - DPE is an emerging technique combining benefits of CSE and epidural with fewer complications.
• PMID 37855310 (2024) - meta-analysis on dexmedetomidine as an epidural adjunct for labour analgesia, showing improved analgesic quality but noting bradycardia risk.
• PMID 39438806 (2024) - meta-analysis comparing ropivacaine vs levobupivacaine for labour epidural analgesia on maternal/fetal outcomes - both comparable, useful for "choice of local anesthetic" discussion.