Explanation: Spearman and Pearson are correlation tests.
Pearson is Parametric. Spearman is non‐parametric

Explanation: Figures quoted vary from 1 in 600 to 1 in 2000

Explanation: The question is asking which test is parametric

Explanation: Medics often think that RCT's are the gold standard of all studies. In terms of
evaluating a therapy or intervention RCTs are the gold standard and top the hierarchy of
evidence. This is not the case when evaluating prognostic tests which are best assessed by cohort studies

Explanation: Anti‐phospholipid syndrome is an autoimmune diseases where antibodies bind to phospholipid proteins on the plasma membrane.Proteins that are bound include anticoagulants Protein C, Protein S and Factor V leading to a hyper‐coagulable state.
PASS‐MRCOG | Epidemiology Lupus anticoagulant (prothrombotic antibody. Most people with Lupus don't have it. Is primary association is with antiphospholipid syndrome) binds prothrombin and cleaves it into the coagulant thrombin Antiphospholipid syndrome prevalence in the obstetric population is around 3%. In patients with recurrent miscarriage it is 15%.

Explanation: Sensitivity = 84 / 84 +6 = 0.93
Specificity = 40 / 40 +2 = 0.95
PPR = 84/84 +2 = 0.97
NPR = 40/40+6 = 0.86
LR+ = Sensitivity/ (1‐Specificty) = 18.6
LR‐ = (1‐Sensitivity) / Specificity = 0.07

Explanation: Sensitivity = 84 / 84 +6 = 0.93
Specificity = 40 / 40 +2 = 0.95
PPV = 84/84 +2 = 0.97
NPV = 40/40+6 = 0.86
LR+ = Sensitivity/ (1‐Specificty) = 18.6
LR‐ = (1‐Sensitivity) / Specificity = 0.07

Explanation: Increasing sample size decreases type 2 errors and increases power of the results. Sensitivity and specificity of the test should remain constant regardless of sample size. Confidence intervals are applied by a statistician and are dependent on the mean.

Explanation: The answer is A

Explanation: The answer is E

Explanation: The RCOG Green-top guidelines state successful VBAC after a single c-section is 72-76%.If a patient has had a previous successful VBAC the figure is 87-90%
The success rate is lower if any of the following are present:
 Induced labour
 No previous vaginal birth
 Obesity (BMI >30)
 Previous C-section for dystocia

Explanation: Medics often think that RCT's are the gold standard of all studies. In terms of
evaluating a therapy or intervention RCTs are the gold standard and top the hierarchy of
evidence. This is not the case when evaluating diagnostic tests or assessing prognosis.

Explanation: The answer is D

Explanation: Pregnancy reduces the risk of fibroids
COCPs are not thought to have a significant effect on prevalence but evidence is conflicting
Obesity, Black ethnicity and early puberty all increase the risk of fibroids

Explanation: When assessing treatment or intervention a randomised control trial is the gold
standard. Note if assessing prognosis or diagnostic tests Cohort and Cross Sectional Analysis
(AKA cross sectional study) respectively are optimal

Explanation: Don't get absolute and relative risk confused. Absolute risk is the actual risk. In this case 20 in 100 or 20%.
Relative risk is a ratio of risk comparing risk in the exposed and control groups, in this case relative risk would be 2

Explanation: Ovarian cancer is the 5th most common cancer among women in the Uk with an incidence of 22 cases per 100,000 in the UK. It should be noted that ovarian tumours are very common. According to the RCOG greentop guidelines (No 62) up to 10% of women in the UK will have surgery for an ovarian mass. In premenopausal women
almost all ovarian tumours are benign

Explanation: OC Affects 0.7% pregnancies in England Itching in general affects 23% of
pregnancies

Explanation: UK Incidence OASIS:
 Primiparous 6.1%
 Multiparous 1.7%
 Overall 2.9%

Explanation: The answer is B
In the exam its often useful to draw the table above

Explanation: The number of stillbirths and deaths in the first week of life per 1000 live
births According to WHO the perinatal period commences at 22 completed weeks (154 days) of gestation and ends seven completed days after birth The UK national figure is about 8 per 1,000 and varies markedly by social class with the highest rates seen in Asian women

Explanation: Sensitivity = 84 / 84 +6 = 0.93
Specificity = 40 / 40 +2 = 0.95
PPR = 84/84 +2 = 0.97
NPR = 40/40+6 = 0.87
LR+ = Sensitivity/ (1‐Specificty) = 18.6
LR‐ = (1‐Sensitivity) / Specificity = 0.07

Explanation: WHO and CMACE consider maternal death to have occurred during pregnancy or
within 42 days of termination of pregnancy.
Maternal death is the death of a woman while pregnant or within 42 days of termination of
pregnancy, irrespective of the duration and site of the pregnancy, from any cause related to or
aggravated by the pregnancy or its management but not from accidental or incidental causes.
To facilitate the identification of maternal deaths in circumstances in which cause of death
attribution is inadequate, a new category has been introduced: Pregnancy‐related death is
defined as the death of a woman while pregnant or within 42 days of termination of pregnancy,
irrespective of the cause of death

Explanation: The Green-top guidelines regarding Vaginal Birth After C-section (VBAC) state
the following risks with VBAC:
 2-3/10,000 additional risk of birth-related perinatal death
 8 in 10,000 infant developing hypoxic ischaemic encephalopathy
 22-74 in 10,000 Risk of uterine rupture (previous lower segment c-section)
 1% additional risk of either blood transfusion or endometritis

VBAC reduces the risk of:
 Reduces risk the baby will have respiratory problems after birth: rates are 2-3% with
planned VBAC and 3-4% with ERCS

Explanation: HG occurs in approximately 1.5% of pregnancies (range is 0.5‐3.0%)

Explanation: Factors shown to decrease risk of ovarian cancer are:
 Oral contraceptive use
 Higher Parity
 Breast feeding
 Hysterectomy
 Tubal Ligation
 Statins
 SLE

Explanation: According to the Green‐top guideline No 45 the risk of uterine rupture with
Vaginal Birth After C‐section (VBAC) is 22‐74 per 10,000.
Remember if asked this in the exam the RCOG may ask the most appropriate risk figure from a list and may use different units e.g. as risk per 1000 or as a percentage. The correct answer may be written as 2 ‐ 8 in 1000 or 0.2 ‐ 0.8%.

Explanation: UK Incidence OASIS:
 Primiparous 6.1%
 Multiparous 1.7%
 Overall 2.9%

Explanation: Most studies into fibroid prevalence have occurred in the US. It has been shown
in a number of studies that African‐American women have a 2‐3 times more likely to develop
fibroids when compared to caucasian women.
Black women are also more likely to develop fibroids at a younger age. In most populations
fibroids are unusual below the age of 30 but this is not uncommon in black women for these to
develop in the 20's.

Explanation: Figures quoted vary from 1 in 40,000 to 1 in 50,000 pregnancies.
Cure rates are 98‐100% in the UK.

Explanation: The average age at diagnosis reflects which age group which is responsible for the most cases of uterine cancer. The average age at diagnosis is around 60 in the UK and the most cases of uterine cancer is seen in the 60‐64 age group (see the graph).
It should be noted the incidence rate (cases per 100,000) is highest in the 70‐74 age group.

Explanation: Apart from PCOS all of the above have some evidence (some of it limited) that
they decrease the risk of endometrial cancer.
Risk Factors for Endometrial Cancer:
 PCOS (2.8 ties higher in PCOS patients)
 Obesity (BMI >30 increases risk by 2.5 times)
 Late menopause
 Early Menarche
 HRT
 Nulliparous
 Diabetes (60% higher incidence in diabetics v non-diabetics)
 Parkinsons
 Tamoxifen use
 Diethylstilbestrol use

Explanation: Standard Error of the Mean = Standard Deviation / square root of sample size
SEM = SD/ square root of n
SEM = 20/200 (200 is the square root of 40,000)
SEM = 0.1

Explanation: Assuming a normal distribution, we can state that 95% of the sample mean would
lie within 1.96 SDs above or below the population mean.
For simplicity or to calculate a quick estimate you can use 2 rather than 1.96
Calculation of 95% CI for mean = (mean ‐ 1.96xSEM) to (mean +1.96xSEM)
Upper CI limit = mean + (1.96 x SEM)
Lower CI limit = mean ‐ (1.96 x SEM)
SEM = 8

SEM x 1.96 = 15.68
95% CI = (110‐15.68) to (110+15.68)
95% CI = 94.32 ‐ 125.68

Explanation: Of the factors listed above only HRT has been shown to increase ovarian cancer risk.

Factors shown to decrease risk of ovarian cancer are:
 Oral contraceptive use
 Higher Parity
 Breast feeding
 Hysterectomy
 Tubal Ligation
 Statins
 SLE

Explanation: Uterine fibroids are the most common non‐cancerous tumours in women of
childbearing age. Although studies are limited studies have shown Approximately 60% of black women had detectable fibroids by 35 years of age; this increased to approximately 80% by 49 years of age. Approximately 40% of white women had detectable fibroids by 35 years of age; this increasedto 70% by 49 years of age.

Explanation: Two types of likelihood ratios exist ‐ positive (LR+) and negative (LR‐).
Positive likelihood ratios tell us how likely a disease is if the test is positive, while the negative likelihood ratio tells us how unlikely a disease is if the test is negative.
They are calculated as:
LR+ = Sensitivity / (1 ‐ Specificity)
LR‐ = (1‐ Sensitivity) / Specificity
A ÷ (A+C) is the calculation for sensitivity
D ÷ (B+D) is the calculation for specificity
A ÷ (A+B) is the calculation for positive predictive value NOTE It has been noted the RCOG may ask you for the likelihood ratio and doesn't specifypositive or negative. They have simply used sensitivity/specificity to calculate this. I can't find any statistical resources that support using this calculation method

Explanation: here are about 11,800 ectopic pregnancies in the UK each year, with an ectopic pregnancy occurring in about 11 in 1000 pregnancies.
Mortality rates for ectopic pregnancy in the UK are 2 per 1000.
The majority of ectopics are tubal with non‐tubal ectopics accounting for only 3‐5% of ectopic pregnancies. The typical distribution is shown below

Explanation: The risk of fibroids is actually reduced by pregnancy and decreases with an
increasing number of pregnancies.
Fibroids are not seen before puberty. Prevalence increases from puberty until menopause

Explanation: The maternal mortality ratio is the number of maternal deaths per 100,000 live
births.
Maternal deathis defined by the WHO as the death of a woman while pregnant or within 42
days of termination of pregnancy, irrespective of the duration and site of the pregnancy, from
any cause related to or aggravated by the pregnancy or its management but not from
accidental or incidental causes
Live birthis defined by the WHO as the complete expulsion or extraction from its mother of a
product of conception, irrespective of the duration of the pregnancy, which, after such
separation, breathes or shows any other evidence of life ‐ e.g. beating of the heart, pulsation of
the umbilical cord or definite movement of voluntary muscles ‐ whether or not the umbilical
cord has been cut or the placenta is attached. Each product of such a birth is considered live
born

Explanation: It would be a little unfair of the RCOG to ask the leading cause of mortality as this changes and the top 3 causes swap places. The most recent data state Sepsis is the most common cause whereas the most recent Green Top Guideline (published in 2009) have VTE as the most common cause (using data from 2003‐2005). Of the options listed haemorrhage is least common

Explanation: The Green-top guidelines regarding Vaginal Birth After C-section (VBAC) state the following risks with VBAC:
 2-3/10,000 additional risk of birth-related perinatal death
 8 in 10,000 infant developing hypoxic ischaemic encephalopathy
 22-74 in 10,000 Risk of uterine rupture (previous lower segment c-section)
 1% additional risk of either blood transfusion or endometritis
VBAC reduces the risk of:
 Reduces risk the baby will have respiratory problems after birth: rates are 2 to 3% with
planned VBAC and 3 to 4% with ERCS

Explanation: 70% of pregnancies with a single episode of RFM are uncomplicated

Explanation: Sepsis is now the most common cause of maternal death in the UK based on
recent figures. Prior to that Thrombosis was the most common cause. Eclampsia is the other
main source of mortality.
Being overweight (BMI 25‐30) has been shown to be increase risk of VTE. It is a weak risk factor
however and in terms of risk stratification of pregnant women for thromboprophylaxis a BMI of
>30 is considered a positive risk factor for PE by both the RCOG and SIGN (see the table)

Explanation: Hypothyroidism is a recognised cause of raised prolactin. In fact it is the most
common cause.

Explanation: Relative risk of VTE in pregnancy is increased 4 to 6 fold in pregnancy according to
the 2009 Greentop guidelines. The risk is increased further in the postpartum period and some
sources quote relative risk increased up to 10 fold.
Absolute risk of VTE in pregnancy and the puerperium is low at 1‐2/1000 pregnancies
Incidence of Pulmonary Embolism in the UK is 1.3/10,000 maternities

Explanation: Sensitivity = 84 / 84 +6 = 0.93
Specificity = 40 / 40 +2 = 0.95
PPR = 84/84 +2 = 0.97
NPR = 40/40+6 = 0.86
LR+ = Sensitivity/ (1‐Specificty) = 18.6
LR‐ = (1‐Sensitivity) / Specificity = 0.07

Explanation: First calculate the prevalence in the control and exposed groups
In smokers: 15/ (15+65) = 0.1875
In Non‐smokers 11/ (77+11) = 0.125
Then divide the prevalence in the exposed by the control group
0.1875/0.125 = 1.5

Explanation: Sensitivity = 84 / 84 +6 = 0.93
Specificity = 40 / 40 +2 = 0.95
PPR = 84/84 +2 = 0.97
NPR = 40/40+6 = 0.86
LR+ = Sensitivity/ (1‐Specificty) = 18.6
LR‐ = (1‐Sensitivity) / Specificity = 0.07

Explanation: The incidence is 1.7 per 10,000 deliveries in the UK.
The USA reports incidence as high as 3 per 1000